1. Field of the Invention
The present invention relates to a shock protection device for a force measuring apparatus, particularly a balance, wherein the force measuring apparatus includes a material block with a stationary parallelogram side member, a deflectable parallelogram side member serving for receiving the force to be measured, two guide members which are bending-elastic in the plane of the parallelogram and which connect the two parallelogram side members, and at least one lever which is connected through a coupling member to the deflectable parallelogram side member.
2. Description of the Related Art
Overload protection devices for balances are known in the art. These devices usually have the purpose of preventing damage to the measuring cell when an excessive load is placed on the weighing dish or when the load drops perpendicularly onto the weighing dish as a result of careless handling. Most known overload protection devices are constructed as stops which limit the vertical travel path of the load receiving means, so that no forces exceeding the computed forces can be introduced into the measuring cell. These devices are of a generally very simple construction and meet their object in an excellent manner.
However, balances cannot only be damaged during weighing, but also during the transport from the manufacturer to the purchaser and possibly also during transport and cleaning on the premises of the user. In that case, forces damaging the balance do not act exclusively in vertical direction onto the force measuring apparatus, but in all possible directions inclined relative to the vertical direction. In order to prevent high acceleration values to act on the force measuring apparatus during shipment, balances are packed in shock-absorbing materials in a complicated and, thus, expensive manner. Such packing materials are very voluminous and, therefore, require a large and also expensive transportation volume, particularly in the case of world wide shipment. Nevertheless, they only provide limited protection.
It is also possible to secure sensitive parts of the balance prior to shipment by means of screws. However, this means that an additional operation is required at the manufacturer and that the balance can only be operated by the purchaser and user when the screws of the transport securing means have been loosened or removed. However, this means that an intervention has to be carried out in the balance which has been calibrated by the manufacturer and that, furthermore, additional time is required for putting the balance in operation.
In modern force measuring apparatus, as described, for example, in DE-A1-4305426, the parallelogram side members, the guide members and the coupling member are frequently constructed of a single-piece material block. The bending points which connect the individual elements to each other have a thickness which is only a few hundreds of a millimeter to a few tenth of a millimeter. Consequently, it is extremely important that these precise elements are protected against the influence of shock.